Protection of trees

ABSTRACT

A method for the protection of trees of the families Musaceae or Plantanginaceae from destructive pests whereby the trees to be protected share a common root system.

This invention relates to a new method of protecting trees of thefamilies Musaceae (banana) and Plantanginaceae (plantains) from harmfulor destructive pests.

Global regulatory requirements are becoming more and more demanding withrespect to the use of pesticides particularly with respect to unmanagedor unnecessary pesticide residues. Thus there exist mutuallycontradictory requirements of farmers in that the need to controldestructive pests very thoroughly demands that more pesticides be used,while increasing pressures from regulatory agencies demand that lesspesticides be used. These regulatory demands are aimed to protect thesafety and health of agricultural workers and the general public. Italso well known that the general public would like less chemicalresidues on fruits and vegetables.

A particular consequence of this situation is that there is anincreasing need to have more efficient methods of protection of bananatrees and plantain trees. It is well known that such fruit-producingtrees attract a large number of pests, particularly destructive insectsand nematodes.

A common technique for cultivating banana trees or plantain trees is bygrowing them on large blocks or plantations. The trees are disposed asmother plants having a series (for example 1 to 5, generally 1 to 3) offollowers or peeps, that is daughter plants, growing from the corm (thatis, the base of the pseudotrunk) of the mother plant. In this respectthe mother and daughter plants share a common root system. At anappropriate time before the harvest of the fruit of the mother plants ortrees, all the daughter plants are removed except one per mother plantwhich are deemed by the grower to have the best chances of survival.Such a practice allows the next generation of banana or plantain plantsto be readily produced. The removal of the daughter plants is possibleafter the harvest of the mother plants, but it is agronomicallypreferred to remove them beforehand.

The fruits of the banana trees are harvested by cutting off the bunchesof fruit. Afterwards, the mother trees are cut to remove the canopies.The pseudotrunks which are left are generally in a height range from 0.5meters to 2.5 meters. Such a practice facilitates the growth of thedaughter plants. The mother pseudotrunk is then left to decay or is cutdown in stages until only a daughter pseudotrunk remains.

Therefore there exists a need to provide an improved method ofprotection for daughter banana trees and plantain trees from pests whichis efficient against destructive pests, especially insects and nematodesand whereby the interval from the treatment of said trees by a pesticideto harvest is as long as possible and whereby the worker exposure is ata minimal level. It has now been found that these needs may be met inwhole or in part by means of the instant invention.

According to the invention, a pesticide is found to be mostadvantageously applied onto or into the pseudotrunk of the cut mothertree in order to protect the daughter tree. In another embodiment, afterthe initial removal of the canopy of the mother tree the daughter plantsmay be allowed to develop and the mother pseudotrunk gradually reducedin size by subsequent cuts. A pesticide may be applied onto or into themother pseudotrunk at any point during this time including when themother pseudotrunk has been effectively removed. However, it is mostadvantageous to apply the pesticide early in the development of thedaughter plant in order to maximise the treatment-harvest time interval.

The instant invention is related to a method for the protection of twoor more trees of the families Musaceae or Plantanginaceae fromdestructive pests wherein the trees to be protected share a common rootsystem which method comprises:

(a) cutting one of the trees sharing the said root system to remove itsfruit and

(b) then introducing a pesticide into the said cut tree.

The pesticide may be introduced into any portion of the said cut tree.According to a feature of the invention, the pesticide is introducedinto the cut of the tree. According to another feature of the invention,the tree is cut to remove its canopy after the removal of its fruit andbefore introducing pesticide. The pesticide is, in a preferred featureof the invention, then introduced into the cut of the tree formed by theremoval of the canopy.

The pesticide is generally an insecticide, nematicide, fungicide orplant growth regulator, preferably an insecticide or nematicide. Thepesticide is generally translocatable and more preferably water solubleat ambient temperature, the water solubility being generally higher than0.5 g/l, preferably higher than 2 g/l at ambient temperature. Thepesticide can be provided in a formulation that is generallytranslocatable and more preferably water soluble at ambient temperature.

Those species of banana or plantain trees to be preferably protectedaccording to the present invention are Musa textilis, Musa sapientum, orMusa paradisica.

The pesticide is generally introduced into the tree from zero to aboutthirty days after one of the trees is cut, preferably from about one toabout seven days and even more preferably from about two to about threedays.

A preferred group of insecticides or nematicides according to theinvention are carbamates. Carbamates are a well-known group ofpesticides: those skilled in the art will recognise these in ThePesticide Manual 10th ed., edited by C. Tomlin, British Crop ProtectionCouncil, United Kingdom, 1994. A preferred group of carbamates areN-methyl carbamates, that is those substances that possess thesubstituent --OC(O)NHMe. A particularly preferred carbamate that can beused according the instant invention is2-methyl-2-(methylthio)propionaldehyde O-methylcarbamoyloxime(aldicarb). Other carbamates that can be used according to the inventionare 2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate (carbofuran)and N,N-dimethyl-2-methylcarbamoyloxyimino-2-(methylthio)acetamide(oxamyl). A carbamate can be used alone or in combination with otherpesticides.

Other insecticides or nematicides that can be used according to theinstant invention either alone or in combination with other pesticidesinclude:

nitromethylenes or nitroimines including1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine(imidacloprid);

cyanoimines including (E)-N¹ - (6-chloro-3-pyridyl)methyl!-N² -cyano-N¹-methylacetamidine (acetamiprid); and

organophosphates including S,S-di-sec-butyl O-ethyl phosphorodithioate(cadusafos);

(RS)-S-sec-butyl O-ethyl 2-oxo-1,3-thiazolidin-3-ylphosphonothioate(fosthiazate); and

O-ethyl S,S-dipropyl phosphorodithioate (ethoprophos).

Other insecticides or nematacides that can be used according to theinstant invention either alone or in combination with other pesticidesinclude compounds of formula (I): ##STR1## in which:

R₁ is --CN or methyl;

R₂ is --S(O)_(n) R₃ ;

R₃ is alkyl or haloalkyl;

R₄ represents a hydrogen or halogen atom or a member of a groupconsisting of --NR₅ R₆, --S(O)_(m) R₇, --C(O)O--R₇, alkyl, haloalkyl,--OR₈ and --N═C(R₉)(R₁₀);

R₅ and R₆ independently represent the hydrogen atom or an alkyl,haloalkyl, --C(O)alkyl, alkoxycarbonyl or --S(O)_(r) CF₃ radical; or R₅and R₆ can together form a divalent alkylene radical which can beinterrupted by one or two divalent heteroatoms, such as oxygen orsulfur;

R₇ represents an alkyl or haloalkyl radical;

R₈ represents an alkyl or haloalkyl radical or a hydrogen atom;

R₉ represents an alkyl radical or hydrogen atom;

R₁₀ represents a phenyl or heteroaryl group which is unsubstituted orsubstituted by one or more halogen atoms or a member of the groupconsisting of --OH, --O-alkyl, --S-alkyl, cyano, and alkyl;

X represents a trivalent nitrogen atom or a --C--R₁₂ radical, the otherthree valences of the carbon atom forming part of the aromatic ring;

R₁₁ and R₁₂ represent, independently of one another, a hydrogen orhalogen atom;

R₁₃ represents a halogen atom or a haloalkyl, haloalkoxy, --S(O)_(q) CF₃or SF₅ group;

m, n, q, and r represent, independently of one another, an integer equalto 0, 1, or 2;

provided that, when R₁ is methyl, then R₃ is haloalkyl, R₄ is --NH₂, R₁₁is --Cl, R₁₃ is CF₃ and X is N.

By the term "alkyl" is meant carbon chains of from one to six carbonatom that are either linear or branched chains. By the term "divalentalkylene" is meant a carbon chain that attaches at two points to thenitrogen atom of the radical R₄.

A preferred group of compounds of formula (I) is one in which:

R₁ is CN;

R₃ is a haloalkyl radical;

R₄ is NH₂ ;

X is C--R₁₂ ;

R₁₁ and R₁₂ represent, independently of one another, a halogen atom; and

R₁₃ is a haloalkyl radical.

A most highly preferred compound of formula (I) is5-amino-1-(2,6-dichloro 4-trifluoromethyl phenyl)4trifluoromethylsulfinyl-3-cyanopyrazole.

Compounds of formula (I) may be prepared according to known processes,for example as described in International Patent Publications No. WO87/3781, 93/6089, and 94/21606 as well as in European PatentApplications 295117, 403300, 385809 or 679650, German Patent Publication19511269 and U.S. Pat. Nos. 5,232,940 and 5,236,938 or other processaccording to the knowledge of a man skilled in the art of chemicalsynthesis.

Pests that may be controlled according to the instant invention includeCosmopolites sordidus (banana weevil), Radopholus similis (burrowingnematode), Helicotylenchus multicinctus (Spiral nematode), Meloidogyneincognita (Rootknot nematode) and pests of the families Heteroderidaeand Thripidae.

Fungicides that may be used according to the instant invention include:

methyl 1-(butylcarbamoyl)benzimidazol-2-ylcarbamate (benomyl);

triazoles including (±)-1-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolan-2-ylmethyl!-1H-1,2,4-triazole(propiconazole); and

1-(2RS,4RS:2RS,4SR)-4-bromo-2-(2,4dichlorophenyl)tetrahydrofurfuryl!-1H-1,2,4-triazole(bromuconazole).

Plant growth regulators that may be used according to the instantinvention include:

a gibberellin such as gibberellic acid or

2-chloroethylphosphonic acid (ethephon).

The amount of pesticide which is used is an effective and agronomicallyacceptable amount per tree. In the case of2-methyl-2-(methylthio)propionaldehyde O-methylcarbamoyloxime,quantities of from 0.01 to 5 g per tree may be appropriate, preferablyfrom 0.3 to 0.9 g per tree.

The introduction of the pesticide in the pseudotrunk of the tree is madeby insertion of a composition, which can be of liquid or solidformulation, preferably solid, in order to reduce worker exposure,especially with compounds having relatively high acute toxicity. A solidformulation is preferred for 2-methyl-2-(methylthio)propionaldehydeO-methylcarbamoyloxime.

Formulations are chosen so as to speed the transmission of the activeingredient into an aqueous phase such as the vascular tissue normallypresent in plants or trees. Formulations are also chosen in order tominimise the exposure of agricultural workers to the pesticide.

Still more preferable are those substantially dustless formulations, forexample those whose particle size is greater than 0.1 mm, preferablyfrom 0.4 to 0.8 mm. Acceptable formulations may be made by mixing theactive ingredient with a polymer, especially a water soluble polymer.Gels may also be used.

The introduction of the pesticide into the pseudotrunk of the mothertree may be made by any suitable means. One possibility is the injectionof the pesticide into the pseudotrunk. Another possibility is to make ordrill holes in the tree and to put therein the formulation and then toplug or stop the holes. The holes may be made on the lateral part of thepseudotrunk, but it is preferred to make the insertion where thepseudotrunk was cut to remove the canopy.

Another method of introduction of the pesticide is to cut a wedge out ofthe pseudotrunk, add the pesticidal formulation and replace the wedgeback into the space from which it came. An especially preferredembodiment of this insertion is to cut the wedge out from the surface ofthe cut made by removing the canopy.

Another embodiment is the insertion into the pseudotrunk of awater-soluble capsule containing a dose of the desired pesticide.

The following non-limiting-example is given to illustrate the invention.

EXAMPLE

Banana trees are grown in a plantation. The trees are disposed as motherplants having a series (1 to 5) of daughter plants growing from thecorm. Just before harvesting the mother plants, the daughter plants areremoved except one daughter plant per mother plant.

The fruit of the banana trees are harvested by cutting the sets offruits. Within one week after this harvest, the pseudotrunks of theseplants are cut to remove the canopies. After two days a wedge is cutfrom the surface resulting from the removal of the canopy of eachpseudotrunk of each mother tree. A dose of 0.5 g per tree of2-methyl-2-(methylthio)propionaldehyde O-methylcarbamoyloxime in theform of a 15% w/w granular formulation is placed in the empty concavespace from which each wedge was removed and the wedges are replaced.

The daughter plants are protected against both nematodes and weevils upto harvest time of the daughter trees which is 35 weeks later thus toprovide economically acceptable fruit The risk of worker exposure isgreatly reduced.

We claim:
 1. A method for the enhanced protection of trees of thefamilies Musaceae or Plantanginaceae from destructive pests, wherein thetrees to be protected share a common root system, which method comprisesthe combination of steps of:(a) cutting at least one of the treessharing the root system to remove its fruit, and (b) then introducing apesticide into at least one of the cut trees, wherein the pesticidecomprises an insecticide or a nematicide and is introduced in aneffective amount per tree.
 2. A method according to claim 1, whereinafter cutting one of the trees to remove fruit in step (a) but beforeintroducing the pesticide in step (b), the cut tree is further cut toremove its canopy.
 3. A method according to claim 1, wherein thepesticide is introduced into the cut of the tree formed by removal ofthe fruit.
 4. A method according to claim 2, wherein the pesticide isintroduced into the cut of the tree formed by the removal of the canopy.5. A method according to claim 1, wherein the pesticide is introducedinto a lateral portion of the tree.
 6. A method according to claim 1,wherein the pesticide is introduced from zero to about thirty days afterthe tree is cut.
 7. A method according to claim 1 wherein the pesticideis generally translocatable at ambient temperature.
 8. A methodaccording to claim 1 wherein the pesticide is provided in a formulationwhich is water soluble at ambient temperature.
 9. A method according toclaim 1 wherein the trees are either Musa textilis, Musa sapientum, orMusa paradisica.
 10. A method according to claim 1, wherein theinsecticide or nematicide is a carbamate.
 11. A method according toclaim 1,wherein the insecticide or nematicide is 2-methyl-2-(methylthio)propionaldehyde O-methylcarbamoyloxime or2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate.
 12. A methodaccording to claim 11 wherein the amount of 2-methyl-2-(methylthio)propionaldehyde O-methylcarbamoyloxime or2,3-dihydro-2,2-dimethylbenzofuran-7yl methylcarbamate used per tree isfrom 0.01 g and 5 g per tree.
 13. A method according to claim 1 whereinthe insecticide or nematicideis:1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine(imidacloprid); (E)-N¹ - (6-chloro-3-pyridyl)methyl!-N² -cyano-N¹-methylacetamidine (acetamiprid);N,N-dimethyl-2-methylcarbamoyloxyimino-2-(methylthio)acetamide (oxamyl);S,S-di-sec-butyl O-ethyl phosphorodithioate (cadusafos);(RS)-S-sec-butyl O-ethyl 2-oxo-1,3-thiazolidin-3-ylphosphonothioate(fosthiazate); or O-ethyl S,S-dipropyl phosphorodithioate (ethoprophos).14. A method according to claim 1 wherein the pesticide used is in asolid or liquid formulation.
 15. A method according to claim 14 whereinthe formulation is substantially dustless.
 16. A method according toclaim 14 wherein the formulation has a particle size greater than 0.1mm.
 17. A method according to claim 14, wherein said pesticide is asolid formulation.
 18. A method according to claim 1, wherein saidpesticide is 2-methyl-2-(methylthio) propionaldehyde O-methylcarbamoyleoxime.
 19. A method according to claim 12, wherein said amount is from0.3 g to 0.9 g per tree.
 20. A method according to claim 14, whereinsaid formulation is a solid formulation.
 21. A method according to claim16, wherein said particle size is from 0.4 to 0.8 mm.
 22. A methodaccording to claim 10, wherein said carbamate is an N-methyl carbamate.23. A method according to claim 1, wherein the pesticide comprises anitromethylene or nitroimine pesticide.
 24. A method according to claim1, wherein the pesticide comprises a cyanoimine pesticide.
 25. A methodaccording to claim 1, wherein the pesticide comprises an organophosphatepesticide.